We have optimized the oligonucleotide primer design for efficient mouse scFv cloning. With the newly-designed primers, it has been possible to successfully clone the variable domains of both the light chain and heavy chain of anti-ETS1 monoclonal antibody E44 and anti-ETS1 mouse spleen antibodies. A "Universal Immuno-PCR" method has been developed, based on the recently described procedure, "Immuno-PCR." This is, thus far, the most sensitive method available for antigen detection and can be applied to various laboratory and/or clinical studies or diagnosis.